Temperature control through thermal recycle

Abstract

An excess heat-generating element is coupled to a heat sink through a heat conduction path. A thermal switch is mounted in the heat conduction path. A temperature-sensitive element is coupled to the heat conduction path on a same side of the thermal switch as the excess heat-generating element. A temperature monitor is mounted adjacent the temperature-sensitive element. A temperature controller has an input coupled to the temperature output of the temperature monitor and an output control line coupled to an input of the thermal switch. The temperature controller switches off the thermal switch, in response to detecting a temperature below a temperature threshold from the temperature output. When the thermal switch it off, it impedes heat flow from the excess heat-generating element to the heat sink, and the heat flow is redirected to increase heat flow from the excess heat-generating element to the heat-sensitive element.

What is claimed is: 
     
       1. An apparatus for beam steering in a Light Detection and Ranging (LiDAR) system of an autonomous vehicle, the apparatus comprising:
 a printed circuit board; 
 at least one of a laser and a mirror assembly mounted on the printed circuit board; 
 a thermistor mounted adjacent the one of a laser and a mirror assembly and having a temperature output; 
 a LiDAR chip, mounted on the printed circuit board, which produces excess heat; 
 a heat sink; 
 a heat conduction path coupled to the LiDAR chip and to the one of a laser and a mirror assembly; 
 a thermal switch coupled between the heat conduction path and the heat sink; and 
 a temperature controller having an input coupled to the temperature output of the thermistor and having an output control line coupled to an input of the thermal switch, the temperature controller being configured to switch off the thermal switch, in response to detecting a temperature below a temperature threshold from the temperature output of the thermistor, to impede heat flow from the LiDAR chip to the heat sink, and increase heat flow from the LiDAR chip to the one of a laser and a mirror assembly. 
 
     
     
       2. The apparatus of  claim 1  wherein the thermal switch comprises a Thermoelectric Cooler (TEC). 
     
     
       3. The apparatus of  claim 1  wherein the LiDAR chip comprises one of a power module or a controller. 
     
     
       4. The apparatus of  claim 1  wherein the heat conduction path comprises at least one metal trace. 
     
     
       5. The apparatus of  claim 1  wherein the thermal switch has one or more positions between on and off. 
     
     
       6. The apparatus of  claim 1  further comprising an active heat generator coupled to the one of a laser and a mirror assembly. 
     
     
       7. The apparatus of  claim 1  wherein the thermal switch is a single stage TEC. 
     
     
       8. An apparatus comprising:
 an excess heat-generating element; 
 a heat sink; 
 a heat conduction path coupling the excess heat-generating element to the heat sink; 
 a thermal switch mounted in the heat conduction path; 
 a temperature-sensitive element coupled to the heat conduction path on a same side of the thermal switch as the excess heat-generating element; 
 a temperature measurement device mounted adjacent the temperature-sensitive element and having a temperature output; and 
 a temperature controller having an input coupled to the temperature output of the temperature measurement device and having an output control line coupled to an input of the thermal switch, the temperature controller being configured to switch off the thermal switch, in response to detecting a temperature below a temperature threshold from the temperature output of the temperature measurement device, to impede heat flow from the excess heat-generating element to the heat sink, and increase heat flow from the excess heat-generating element to the temperature-sensitive element. 
 
     
     
       9. The apparatus of  claim 8  wherein the temperature-sensitive element comprises one of a laser and a mirror assembly. 
     
     
       10. The apparatus of  claim 9  wherein the temperature controller comprises:
 a temperature measurement circuit having an input coupled to the temperature output of the temperature measurement device; 
 a difference amplifier having a first input coupled to an output of the temperature measurement circuit and a second input coupled to a set temperature corresponding to a minimum target temperature; 
 a compensation network coupled to an output of the difference amplifier; and 
 an H-bridge switch coupled to an output of the compensation network and having a control output coupled to an input of the thermal switch. 
 
     
     
       11. The apparatus of  claim 8  wherein the thermal switch comprises a Thermoelectric Cooler (TEC). 
     
     
       12. The apparatus of  claim 8  wherein the temperature-sensitive element comprises an optical assembly including a micro mirror, mounted to scan a laser beam from a laser across an environment to be detected; and further comprising:
 a filter mounted to intercept a reflected beam directed to the micro mirror, the filter having a passband corresponding to a designated wavelength range. 
 
     
     
       13. The apparatus of  claim 8  wherein the excess heat-generating element comprises one of a power module or a controller. 
     
     
       14. The apparatus of  claim 8  wherein the heat conduction path comprises at least one metal trace. 
     
     
       15. The apparatus of  claim 8  wherein the thermal switch has one or more positions between on and off. 
     
     
       16. The apparatus of  claim 8  further comprising an active heat generator coupled to the temperature-sensitive element. 
     
     
       17. A method comprising:
 generating excess heat with an excess heat-generating element; 
 directing the excess heat to a heatsink through a thermal switch; 
 coupling the excess heat-generating element to a temperature-sensitive element with a thermal path; 
 measuring a temperature adjacent the temperature-sensitive element with a temperature-measuring element to provide a measured temperature; 
 monitoring the measured temperature with a temperature controller; 
 in response to the measured temperature being below a threshold, controlling the thermal switch with the temperature controller to redirect the excess heat along a thermal path to the temperature-sensitive element. 
 
     
     
       18. The method of  claim 17  further comprising actively heating the temperature-sensitive element with an active heating element. 
     
     
       19. The method of  claim 17  further comprising:
 scanning a laser beam across an environment to be detected with a micro mirror assembly; 
 filtering a reflected beam with a filter having a passband corresponding to a designated wavelength range; and 
 detecting the reflected beam with a photodetector. 
 
     
     
       20. The method of  claim 19  further comprising cooling the temperature-sensitive element when the measured temperature reaches an upper threshold.